While Norman Sherry is still engaged in writing his hugely detailed, three-volume Greene biography comes this deconstructionist effort by the author of studies of Cyril Connolly and Orwell. Shelden began work intending an ``affectionate portrait,'' but ``along the way I kept uncovering unpleasant facts.'' That is a considerable understatement. Shelden has portrayed Greene as an eternal manipulator, of friends as well as of the world press; as a man whose ostensible religion and politics were shams, whose early books--including the much-admired Brighton Rock--contained reprehensible anti-Semitic elements; and, artistically, as a writer who underwent a decline after The Heart of the Matter in 1948, with only occasional glimpses (as in The Human Factor of 1978) of the huge talents he once possessed. Although Greene was renowned for his louche sexual habits (Shelden asserts he could have authored a splendid guide to the world's best brothels), it has not previously been documented that he had homosexual inclinations. Shelden avers that in his hideaway on Capri, he dallied with young boys, and that there are passages in his work that can only be seen as the product of a gay sensibility. Shelden's scrutiny of Greene's work is scrupulous, and certainly suggests that some reassessment of much of it is in order. In the case of Greene's private life, it is clear that his habitual evasiveness and cunning render many of his actions subject to various interpretations. Shelden's book is certainly an impressive brief for the prosecution, even if this most mysterious of contemporary writers continues ultimately to baffle and elude us. Photos not seen by PW. (June)